Affiliation:
1. Department of Molecular and Cell Biology, The University of Texas at Dallas, Richardson, Texas, USA
Abstract
ABSTRACT
FeaR is an AraC family regulator that activates transcription of the
tynA
and
feaB
genes in
Escherichia coli
. TynA is a periplasmic topaquinone- and copper-containing amine oxidase, and FeaB is a cytosolic NAD-linked aldehyde dehydrogenase. Phenylethylamine, tyramine, and dopamine are oxidized by TynA to the corresponding aldehydes, releasing one equivalent of H
2
O
2
and NH
3
. The aldehydes can be oxidized to carboxylic acids by FeaB, and (in the case of phenylacetate) can be further degraded to enter central metabolism. Thus, phenylethylamine can be used as a carbon and nitrogen source, while tyramine and dopamine can be used only as sources of nitrogen. Using genetic, biochemical and computational approaches, we show that the FeaR binding site is a TGNCA-N
8
-AAA motif that occurs in 2 copies in the
tynA
and
feaB
promoters. We show that the coactivator for FeaR is the product rather than the substrate of the TynA reaction. The
feaR
gene is upregulated by carbon or nitrogen limitation, which we propose reflects regulation of
feaR
by the cyclic AMP receptor protein (CRP) and the nitrogen assimilation control protein (NAC), respectively. In carbon-limited cells grown in the presence of a TynA substrate,
tynA
and
feaB
are induced, whereas in nitrogen-limited cells, only the
tynA
promoter is induced. We propose that
tynA
and
feaB
expression is finely tuned to provide the FeaB activity that is required for carbon source utilization and the TynA activity required for nitrogen and carbon source utilization.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
19 articles.
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